Photoelectric discharge device



June 17, 1952 w. H. KLIEVER ET AL 2,601,203

PHOTOELECTRIC DISCHARGE DEVICE Filed 001". 16. 1947 3nventor5 w/uoo H.IfL/EVEI? (Ittorneg Patented June 17, 1952 UN I TED S 'TATE'S PAT E 'N-TF 2,601,208 1 PHOTOEEEGTRIC DISCHARGE DEVICE WaldoH'. KlieverrandNoel T.Stone, Minneapolis;

Minn,

assignors'i to Minneapolis-Honeywell Regulator Com a y, Minneapolis.Minm, a

corporationof:Delaware Application October 16, 1947, Serial No.780g2450;

14 -Glaims. 1,

This invention relates to electron discl'iargedevices of thelightsensitivetype and'espec'ially to those devices wherein the"electrodes form part of the envelope. It is an object of this inventionto devise an electron discharge device of extreme simplicity.

Another object of the invention is to produce an electron dischargedevice of very small. dimensions.

Another object of the; invention is to devise an electron dischargedevice which will have a small number of parts and a sturdy constructionand be capable of taking a great deal of: abuse and still not affect itsoperation.

Another object of the invention isto devisean electron discharge devicewhich will require no lead-in wires into the envelope nor'any prongsnecessitating plugging. said device; into a socket.

Another object of the invention is to devisea photo-electric tube inwhich the light passes through a window mounted to cover" a removedportion of the anode.

These objects are accomplished by designing the electron dischargedevice in such amanner that the anode and cathode electrodes-form partsof the envelope of the device and by making a portion of the anode inthe form of an annulus.

Other objects and advantages will become apparent in the following, moredetailed, descriptionand by reference to the drawings in which:

Figure 1 is a top plan view of a photo-electric tube embodying thefeatures of the invention;

Figure 2 is a cross sectional view of the tube shown in Figure 1 alongthe line 2-z-2 in the'direction of the arrows; and

Figure 3 is a horizontal sectional view of the tube shown in Figure 1taken alongthe'line 3-3 in Figure 2 in thedirection of the arrows.

Referring now to Figure 2, the cathode llland the anode I I are joinedtogether by ashort glass cylinder l2 which acts as a. hollow cylindricalhousin member. A flat circular piece of. glass l3 covers the opening inthe anode I l. A short hollow metal tube I4 is shown joined tor thecathode l6; Acesium pellet capsule I is joined to the cathode Ill by awire IS. A light sensitive surface H is shown on the cathode.

The cathode l9 hasia curved'por'tion shaped in the formof a sphericalsurface so .asto be convex on-the side facing the anode! I. A flatportion-2| of cathode Ill provides a surface or pocket to seat the glasscylinder [2. A bent cylindrical portion 22 perpendicular to the flatportion 21 of cathode Ill centers the cylindricalwall I21 with respectto the light sensitive surface H5 or the cathode. The outside portion ofcathode I0 is bent outwardly'to form a-circular flange 23.

In this drawing,.the cylinder l2 isishown to be glass .but it isunderstood that any satisfactory electrically insulating material woulddo. The glass cylinder I2 is placed onthe fiatv portion 2! of cathodeIt. Cathode I0 is: then heated to approximately 1000 C., whichissufficient to-melt that portion of the glass: cylinder lirestih incontact with cathode I0 and cause the'cylinder l2 and cathode ill tofuse together;

The spherical surface 20' of cathode l0 can then be coated with silverinanymanner desired, for example, plating. A- cesium pellet-which' iscomposed of cesium dichromate and aluminum, calcium, zirconium or anyother'suitable metal is contained between twonickel plates ha'ving twoapertures from the pellet to theoutside. This type of pellet is old inthe art-as shown in Spencer Patent 2,088,070 and: hasbeen described forillustration only. The pellet-capsule l5 is fastened to-cathode In bymeansof wire [6. Its: position in the tube can perhaps be better seen byexamination of Figure 3 which shows the-capsule adjacent to a portion ofthe glass cylinder 12. The reasoning for this positioning will-bedescribed later on in the specification.

The anode l l hasannulus portion 24 which is the operative portion of.the anode receiving the electrons emitted fromthelight sensitive surface ll on cathode I0. A-cylindricalportionie of the anode H is-formedat. right angles. to the annulus portion 24 of. the-anode. The outerportion 26 of the anode ll is be r-it'outwardlyto form a-circu1arflange. Thecylindricalportion-25 and the flange 26 center-the anode llon-the glass cylinder l2. This also has the effect ofcenterlng theannulus portion 24 of the-anode H with respect to-the light sensitivesurface I! of thecathode ID.

A circular member I 13 of: glass is then placed upon'the annulus portion24 of the-anode and fitted against the cylindrical portion 25 ofthe'anode to constitute a window. The circular glass member I3 is thenfused-to the anode l l and the anode is then fused with theglasscylinder I2 by the method already described.-

The general operation of making the surface of the cathode sensitivetolight-is well known, but due to peculiar problems arising from theunique construction of this tube the-processwill be gone over briefly.It is to be'understood; however; that the method to-lie described is butone method which will be satisfactory in making a light sensitivesurface on the cathode;

The silvered surface of the spherical portion 20 of the cathode isoxidized to a depth of approximately 10" Or 10- centimeters. Thisoxidation of the silver is done under approximately 0.1 millimeter ofoxygen pressure.

The tube is then re-evacuated and the cesium pellet is fired at atemperature of approximately 900 0., by means of an induction heater.The cathode l0, anode ll, cylinder I2 and window I3 are all cooled bycold water so that the cesium is caused to condense over the entireinterior surface of the tube. The cesium pellet capsule is placed nearone portion of the glass cylinder [2 so that it may be heated by theinduction heater without necessitating the heating of the cathode i9 andthe anode I I. Due to this positioning the capsule covers a very smallportion of the light sensitive surface of the cathode. When the cesiumis released from the pellet the dichromate combines with the othermetals in the pellet to form aluminum dichromate, calcium dichromate,zirconium dichromate or a dichromate of any other metal which might bepresent. During this operation of firing the cesium pellet it isnecessary to heat the cathode at a temperature below 220 C. so as not todecompose the silver oxide.

The cesium is then driven off the glass wall l2, window [3 and anode l Iby heating them with a jet of hot air at approximately 200 C. This hotair jet is applied by external means, not shown, to the outer surfacesof the glass wall l2 and window 13. The cathode may be kept cool by coldwater causing the cesium to condense on the cathode and combine with thesilver oxide to form a coating of what is believed to be cesium oxide,silver and free cesium.

The tube is then baked which process will drive off the excess cesium.The baking is continued until the tube is at optimum sensitivity whichmust be determined by experience.

The hollow tube I4 provides the aperture for evacuating the envelope,adding the oxygen, and withdrawing the excess cesium. After the envelopehas been evacuated for the last time, the tube I4 is sealed off near thecathode as shown.

Light from a light source is shown to enter through window [3 where itpasses on through until it strikes the photo-sensitive surface I! on thecathode iii. The spherically shaped portion 20 of the cathode l0 causesthe electrons leaving the light sensitive surface I! to be more directlydeflected toward the annulus portion 24 of anode ll. Also this shapeenables the cathode IE! to better withstand the effects of air pressure.Because of the flanged portions 23 and 28 on cathode IB and anode II,respectively, it is possible to position the tube so that these flanges23 and 25 may rest on conductive rings. Electrical contacts could alsobe made to the cathode and anode by means of wires 30 and 3| fastenedonto the flanges 23 and 26 as is shown in Figure 2. As can be seen, thisexternal flange arrangement of the cathode and anode lends itself easilyto a variety of methods for making contact to the electrodes. .Byutilizing the cathode and anode as part of the envelope, it is possibleto make this tube using simple construction and in a very small size andthus it can profitably be used where space is at a premium.

While we have illustrated but one embodiment of the invention, it is tobe understood that modifications may be made without departing from thespirit or scope thereof, and that we wish to limit ourselves only to theextent shown in the appended claims.

We claim as our invention:

1. An electron discharge device comprising an envelope, an annularanode, and an electron emissive cathode forming a portion of a surfaceof a sphere convex toward said anode, said cathode and anode formingportions of said envelope.

2. A photoelectric tube comprising an envelope, an annular anode at thatend of the envelope to be exposed to the light rays, and a photoemissivecathode shaped to form a portion of a surface of a sphere convex towardsaid anode, said cathode and anode being at opposite ends of saidenvelope and forming portions of said envelope.

3. A photoelectric tube comprising an evacuated envelope, an annularanode electrode at one end of the envelope and forming a portion thereofand surrounding that portion of said envelope to be exposed to the lightrays, and a photoemissive cathode shaped to form a portion of a sphereconvex toward said anode and placed at the opposite end of the envelopefrom the anode and forming a portion of said envelope.

4. A photoelectric tube comprising an anode with a portion thereofremoved, a light transmitting member covering the aperture resultingfrom said removed portion of said anode, a light sensitive cathode forimpingement by the light waves, said cathode being convex toward saidanode so that the electrons leaving the light sensitive surface will bedeflected toward said anode, and means positioning said cathode withrespect to said anode in such a manner that said anode and cathode areelectrically insulated from each other.

5. A photoelectric tube comprising an anode with a portion thereofremoved, a light transmitting member covering the aperture resultingfrom said removed portion of said anode, a light sensitive cathode forimpingement by the light waves, said cathode being convex toward saidanode so that the electrons leaving the light sensitive surface will bedeflected toward said anode, and means positioning said cathode withrespect to said anode in such a manner that said anode and cathode areelectrically insulated from each other, said cathode having an aperturetherethrough for evacuating said tube.

6. A photoelectric tube comprising an anode with a portion thereofshaped in the form of an annulus, a member permitting passage of lighttherethrough positioned on said annulus portion of the anode and fusedthereto, a cathode having a light sensitive surface on a portionthereof, said light sensitive surface being circular and shaped in theform of a spherical surface convex toward the anode, and meanspositioning said cathode with respect to said anode in such a mannerthat said anode and cathode are electrically insulated from each other.

7. A photoelectric tube comprising an anode with a portion thereofshaped in the form of an annulus, a member permitting passage of lighttherethrough positioned on said annulus portion of the anode and fusedthereto, a. cathode having a light sensitive surface on a portionthereof, said light sensitive surface being circular and shaped in theform of a spherical surface convex toward the anode, and means, in theshape of a cylinder fused to said anode and cathode, electricallyinsulating said anode from said cathode and centering said annulusportion of said anode with respect to said light sensitive surface onsaid cathode.

8. A photoelectric tube comprising an anode with a portion thereofshaped in the form of an annulus, a member permitting passage of lighttherethrough positioned on said annulus portion of the anode and fusedthereto, a cathode having a light sensitive surface on a portionthereof, said light sensitive surface being circular and shaped in theform of a spherical surface convex toward the anode, a source of photosensitive material supported by said cathode, and means, in the shape ofa cylinder fused to said anode and cathode, electrically insulating saidanode from said cathode and centering said annulus portion of said anodewith respect to said light sensitive surface on said cathode.

9. A photoelectric tube comprising a cylindrical housing member andanode and cathode circular sheet metal discs sealed to opposite ends ofsaid cylindrical member, said anode disc having a deformed portion toprovide a shoulder to fit snugly against said cylindrical member, saidanode having a central aperture therethrough, and a window member oftransparent material sealed within said aperture and covering saidaperture, said cathode having the inner surface thereof coated with aphotoemissive material and having a deformed portion to provide ashoulder to fit snugly against said cylindrical member.

10. A photoelectric tube comprising a cylindrical housing member andanode and cathode circular sheet metal discs sealed to opposite ends ofsaid cylindrical member, said anode disc having a central recessedportion extending into said housing member and providing a shoulder ofthe same exterior diameter as the interior member of said housingmember, said recessed portion having a central aperture therethrough,and a window member of transparent material sealed within said recessedportion and covering said aperture, said cathode having the innersurface thereof coated with a photoemissive material and having theouter portion thereof deformed so as to provide a shoulder closelysurrounding said cylindrical housing member.

11. A photoelectric tube comprising a hollow cylinder of insulatingmaterial, a cathode member comprising a metal disc deformed about theedge thereof to form a pocket for one end of said hollow cylinder andsealed thereto, said cathode having a photoemissive layer formed on thesurface thereof, an anode member comprising a metallic member having anaperture therein, said anode member being deformed with an innershoulder arranged to project within the other end of said hollowcylinder and sealed to the other end of said cylinder, and a window ofelectric insulating material sealed over said aperture.

12. A photoelectric tube comprising a hollow member of insulatingmaterial, a cathode member comprising a metal member deformed about theedge thereof to form a pocket for one end of said hollow member andsealed thereto, said cathode having the central portion thereofprojecting within said hollow member and having a photoemissive layerformed on the surface thereof, an anode member comprising a metallicmember having an aperture therein, said anode member being deformedabout the edge thereof to provide a shoulder arranged to project withinthe other end of said hollow member, and a window of insulating materialsealed in said aperture.

13. A photoelectric tube comprising, a cathode member comprising a metalmember deformed about the edge thereof to form a pocket, said cathodemember having a photoemissive layer formed on the surface thereof, ametallic anode, and a hollow member of light pervious insulatingmaterial sealed at one end in said pocket so that said cathode projectswithin said hollow member and supporting said anode so that said anodeis parallel to said cathode with a portion of said anode outside of saidhollow member and with the projected area of said anode within saidmember on said cathode being less than the area of said cathode, saidphotoelectric tube being sealed at the end opposite said cathode bymeans formed of light pervious insulating material so that light maypass through the last named sealed end to said cathode.

14. A photoelectric tube comprising, a cathode member comprising a metalmember deformed about the edge thereof to form a pocket, said cathodemember having a photoemissive layer formed on the surface thereof, aring-shaped metallic anode, a hollow member of light pervious insulatingmaterial sealed at one end in said pocket so that the photoemissivesurface of said cathode projects within said hollow member andsupporting said anode so that the plane of said anode is parallel tosaid cathode with a portion of said anode projecting outside of saidhollow member, said photoelectric tube being sealed beyond said anode bymeans formed of light pervious insulating material so that light maypass through the open portion of said anode to said cathode.

WALDO H. KLIEVER. NOEL 'I'. STONE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,722,280 DeForest July 30, 19292,161,859 Geffcken et al June 13,1939 2,166,124 Breyer July 18, 19392,401,737 Janes June 11, 1946 2,404,343 Henderson et a1. July 16, 19462,431,402 Janes Nov. 25, 1947 FOREIGN PATENTS Number Country Date712,542 France July 22, 1931

